CN113725244A - Image sensor and method for manufacturing the same - Google Patents
Image sensor and method for manufacturing the same Download PDFInfo
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- CN113725244A CN113725244A CN202111005082.5A CN202111005082A CN113725244A CN 113725244 A CN113725244 A CN 113725244A CN 202111005082 A CN202111005082 A CN 202111005082A CN 113725244 A CN113725244 A CN 113725244A
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- H10F39/00—Integrated devices, or assemblies of multiple devices, comprising at least one element covered by group H10F30/00, e.g. radiation detectors comprising photodiode arrays
- H10F39/011—Manufacture or treatment of image sensors covered by group H10F39/12
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- H10F39/00—Integrated devices, or assemblies of multiple devices, comprising at least one element covered by group H10F30/00, e.g. radiation detectors comprising photodiode arrays
- H10F39/011—Manufacture or treatment of image sensors covered by group H10F39/12
- H10F39/014—Manufacture or treatment of image sensors covered by group H10F39/12 of CMOS image sensors
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- H10F39/00—Integrated devices, or assemblies of multiple devices, comprising at least one element covered by group H10F30/00, e.g. radiation detectors comprising photodiode arrays
- H10F39/80—Constructional details of image sensors
- H10F39/803—Pixels having integrated switching, control, storage or amplification elements
- H10F39/8037—Pixels having integrated switching, control, storage or amplification elements the integrated elements comprising a transistor
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Abstract
The invention provides a manufacturing method of an image sensor, which is applied to the technical field of semiconductors. Specifically, a patterned photoresist layer is formed on the semiconductor substrate before a sidewall etching process (forming a first sidewall structure and a second sidewall structure), so that the patterned photoresist layer covers the surface of the semiconductor substrate corresponding to the photodiode region, and then a subsequent etching process is performed, so that the semiconductor substrate corresponding to the photodiode region is prevented from being completely exposed in a plasma environment in the etching process, the surface of the semiconductor substrate corresponding to the photodiode region is prevented from being damaged, and further, dark current caused by surface damage is avoided, and meanwhile, the normal functions of a pixel device region and a logic device region are ensured, and finally, the performance of the image sensor is improved.
Description
Technical Field
The present invention relates to CMOS image sensors in the field of semiconductor technologies, and in particular, to an image sensor and a method for manufacturing the same.
Background
With the rapid development of the new fields such as artificial intelligence, internet of things, industry 4.0 and the like, the demand of the market for a CMOS Image sensor (CMOS Image sensor) is increasing day by day, the performance requirement of the CMOS Image sensor is higher and higher, and an important index of the Image sensing performance is the dark current level. Dark current means that a photodiode (Photo Diode) can still generate charges under the condition of no light at all, and current signals are formed to be read out, and the current signals are reflected as 'white' pixels in image imaging, so that the picture quality is reduced.
For some special application scenes, indexes of application dark current such as monitoring and the like are particularly important, main sources of the dark current include surface damage, silicon body stress, ion implantation damage, lattice defects and the like caused by plasma, for application fields such as monitoring, industrial monitoring, unmanned aerial vehicle shooting and the like with high requirements on picture quality, a large pixel structure is adopted in design, namely the area of a photodiode region is particularly large to obtain enough light entering quantity, the pixel size of the product is usually more than 5 micrometers, even more, the size can be more than ten micrometers, in order to prevent tailing effect, the ion implantation of the photodiode region (PD region) is not too deep, and the dark current caused by the surface damage is particularly obvious under the condition that the product has an overlarge surface area and is shallow.
In the existing image sensor manufacturing process, referring to fig. 1-2, fig. 1-2 are schematic device diagrams in the existing image sensor manufacturing process, in the sidewall etching process, the image sensor undergoes the change process from fig. 1 to fig. 2, and the silicon nitride layer, the oxide layer and the high-temperature thermal oxide layer on the substrate are removed by dry etching, however, the etched photodiode region surface only has a gate oxide layer with the thickness of 10nm, and plasma acting on the surface in the etching process is easy to cause damage, so that dark current is caused, and for products with the pixel size larger than 5 micrometers, the dark current caused by surface damage of the photodiode region is more obvious.
Disclosure of Invention
The invention aims to provide an image sensor and a manufacturing method thereof, which are used for preventing the surface of a photodiode region from being damaged in the manufacturing process of the image sensor, thereby effectively reducing dark current and further improving the image performance of a product.
In a first aspect, to achieve the above object, the present invention provides a method for manufacturing an image sensor, including the following steps:
s1, providing a semiconductor substrate, wherein a pixel device area is defined in the semiconductor substrate and comprises a photodiode area and a transfer transistor area, a first gate structure and a side wall material layer which covers the surface of the first gate structure and extends to cover the surface of the semiconductor substrate corresponding to the photodiode area are sequentially formed on the surface of the semiconductor substrate corresponding to the transfer transistor area, and the surface of the side wall material layer is a nitride layer;
s2, performing an oxygen treatment process on the surface layer of the side wall material layer, which faces away from the first gate structure, so that the surface layer of the side wall material layer, which faces away from the first gate structure, is converted into an oxynitride layer;
s3, forming a patterned photoresist layer, wherein the patterned photoresist layer covers the photodiode region and the surface of the side wall material layer corresponding to a part of the transfer transistor region to expose a part of the side wall material layer corresponding to the transfer transistor region;
s4, etching the exposed side wall material layer by taking the patterned photoresist layer as a mask so as to form a first side wall structure on one side of the first grid structure;
and S5, removing the patterned photoresist layer, and performing subsequent processes on the semiconductor substrate including the side wall material layer covering the photodiode region and part of the transfer transistor region to form the electrical structure of the image sensor.
Further, a device isolation structure and a logic device region separated from the pixel device region by the device isolation structure may be further formed in the semiconductor substrate provided in step S1, and a second gate structure may be formed on a surface of the semiconductor substrate corresponding to the logic device region; the spacer material layer in step S1 may further extend to cover the surfaces of the device isolation structure and the second gate structure.
Furthermore, the side wall material layer can be of a single-layer structure or a double-layer structure.
Further, when the side wall material layer is of a single-layer structure, the material of the side wall material layer may include nitride; when the side wall material layer is of a multilayer structure, the material of the side wall material layer may include an oxide and a nitride which are stacked in sequence.
Further, the process conditions of the oxygen treatment process in the step S2 may include: the temperature range can be 200-300 ℃, the reaction gas can be a mixed gas of oxygen and nitrogen, and the process duration can be 20-90 s.
Further, the process of removing the patterned photoresist layer in step S5 may be a dry etching process; the process conditions of the dry etching process may include: the temperature range is 200-300 ℃, the reaction gas can be plasma gas of oxygen and nitrogen, and the process duration can be 30-90 s.
Further, the step of performing subsequent processes on the semiconductor substrate in the step S5 may include:
s5.1, sequentially depositing an oxide layer, a nitride layer, an interlayer dielectric layer and a patterned hard mask layer on the surface of the semiconductor substrate including the side wall material layer which covers the photodiode region and part of the transfer transistor region;
s5.2, with the hard mask layer as a mask, etching the interlayer dielectric layer and the nitride layer to form corresponding contact holes in the transfer transistor area and the logic device area, wherein the bottoms of the contact holes are exposed out of the tops of the first grid structure or the second grid structure;
and S5.3, forming a conductive plug filled in the contact hole.
Further, the boundary of the patterned photoresist layer formed in the step S3 along a side close to the logic device region may be horizontally spaced from the conductive plug formed in the transfer transistor region by 1/5 to 1/3L, where L may be a width of the conductive plug formed in the transfer transistor region in a direction parallel to the surface of the semiconductor substrate.
Further, in step S4, while forming the first sidewall structure of the first gate structure, second sidewall structures may be formed on two sides of the second gate structure.
In a second aspect, the present invention also provides an image sensor based on the manufacturing method of the image sensor, and in particular, the image sensor can be manufactured by the manufacturing method of the image sensor.
Compared with the prior art, the technical scheme of the invention has the following beneficial effects:
according to the manufacturing method of the image sensor, the patterned photoresist layer is formed on the semiconductor substrate before the side wall etching process (forming the first side wall structure and the second side wall structure) so as to cover the surface of the semiconductor substrate corresponding to the photodiode region, and then the subsequent etching process is performed, so that the semiconductor substrate corresponding to the photodiode region is prevented from being completely exposed in a plasma environment in the etching process, the damage to the surface of the semiconductor substrate corresponding to the photodiode region is avoided, the dark current caused by the surface damage is further avoided, the normal functions of the pixel device region and the logic device region are ensured, and the performance of the image sensor is finally improved.
The image sensor provided by the invention is manufactured by adopting the manufacturing method of the image sensor provided by the invention, the photoresist covers the photodiode area, so that the surface damage of plasma gas in an etching process to the photodiode area is avoided, the dark current caused by the surface damage is avoided, and the performance of the image sensor is improved.
Drawings
FIG. 1 is a schematic diagram of a device in a prior art image sensor manufacturing process;
FIG. 2 is a schematic diagram of a device in a prior art image sensor manufacturing process;
fig. 3 is a schematic flow chart of a method for manufacturing an image sensor according to an embodiment of the present invention;
fig. 4a to 4f are schematic structural diagrams of a method for manufacturing an image sensor according to an embodiment of the present invention during a manufacturing process thereof.
Wherein the reference numerals are as follows:
01-a nitride layer; 02-an oxide layer; 03-high temperature thermal oxidation layer; 04-gate oxide layer; 05-photodiode region; 11-photodiode region; 12-pixel device region; 13-logic device area; 14 a-a first gate structure; 14 b-a second gate structure; a-a first sidewall structure; 15-device isolation structures; 16-a semiconductor substrate; 17-a gate oxide layer; 18-high temperature thermal oxidation layer; 19-an oxide layer; a 20-nitride layer; 20' -an oxynitride layer; 21-a patterned photoresist layer; 22-an oxide layer; 23-a nitride layer; 24-interlayer dielectric layer; 25-conductive plug.
Detailed Description
As described in the background art, at present, for some special application scenarios, such as monitoring, etc., the index of applying dark current is particularly important, the main sources of dark current include surface damage caused by plasma, silicon bulk stress, ion implantation damage, lattice defects, etc., for application fields with high requirements on picture quality, such as monitoring, industrial monitoring, unmanned aerial vehicle shooting, etc., a large pixel structure is adopted in design, that is, the area of a photodiode region is particularly large to obtain sufficient light input, the pixel size of such products is usually above 5 micrometers, even more, tens of micrometers can be achieved, in order to prevent "tailing effect", the ion implantation of the photodiode region (PD region) is generally not too deep, and the dark current caused by surface damage is particularly significant under the condition that such products have an ultra-large surface area and the ion implantation is shallow.
In the existing image sensor manufacturing process, referring to fig. 1-2, fig. 1-2 are schematic device diagrams in the existing image sensor manufacturing process, in the sidewall etching process, the image sensor undergoes the change process from fig. 1 to fig. 2, a silicon nitride layer, an oxide layer and a high-temperature thermal oxide layer on a substrate are removed by dry etching, however, the surface of an etched photodiode region is only a gate oxide layer with the thickness of 10nm, and plasma in the etching process acts on the surface to easily cause damage, so that dark current is caused, and for products with the pixel size larger than 5 micrometers, the dark current caused by the surface damage of the photodiode region is more obvious, wherein, the 01-nitride layer; 02-an oxide layer; 03-high temperature thermal oxidation layer; 04-gate oxide layer; 05-photodiode region.
Therefore, the invention provides an image sensor and a manufacturing method thereof, which are used for preventing the surface of a photodiode region from being damaged in the manufacturing process of the image sensor, thereby effectively reducing dark current and further improving the image performance of a product. Referring to fig. 3 in detail, fig. 3 is a schematic flow chart of a manufacturing method of an image sensor according to an embodiment of the present invention, and as can be seen from fig. 3, the manufacturing method of the image sensor may specifically include the following steps:
s1, providing a semiconductor substrate, wherein a pixel device area is defined in the semiconductor substrate and comprises a photodiode area and a transfer transistor area, a first gate structure and a side wall material layer which covers the surface of the first gate structure and extends to cover the surface of the semiconductor substrate corresponding to the photodiode area are sequentially formed on the surface of the semiconductor substrate corresponding to the transfer transistor area, and the surface of the side wall material layer is a nitride layer;
s2, performing an oxygen treatment process on the surface layer of the side wall material layer, which faces away from the first gate structure, so that the surface layer of the side wall material layer, which faces away from the first gate structure, is converted into an oxynitride layer;
s3, forming a patterned photoresist layer, wherein the patterned photoresist layer covers the photodiode region and the surface of the side wall material layer corresponding to a part of the transfer transistor region to expose a part of the side wall material layer corresponding to the transfer transistor region;
s4, etching the exposed side wall material layer by taking the patterned photoresist layer as a mask so as to form a first side wall structure on one side of the first grid structure;
and S5, removing the patterned photoresist layer, and performing subsequent processes on the semiconductor substrate including the side wall material layer covering the photodiode region and part of the transfer transistor region to form the electrical structure of the image sensor.
That is, in the method for manufacturing an image sensor provided by the present invention, a patterned photoresist layer is formed on a semiconductor substrate before a sidewall etching process (forming a first sidewall structure and a second sidewall structure) to cover the photoresist layer on the surface of the semiconductor substrate corresponding to a photodiode region, and then a subsequent etching process is performed to prevent the semiconductor substrate corresponding to the photodiode region from being completely exposed to a plasma environment in the etching process, thereby avoiding damage to the surface of the semiconductor substrate corresponding to the photodiode region, further avoiding dark current caused by surface damage, ensuring normal functions of a pixel device region and a logic device region, and finally improving the performance of the image sensor.
The image sensor and the method for manufacturing the same according to the present invention will be described in further detail with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention.
Fig. 4a to 4f are schematic structural diagrams illustrating a manufacturing method of an image sensor in an embodiment of the invention during a manufacturing process thereof.
In step S1, and with particular reference to fig. 4a, a semiconductor substrate 16 is provided, the semiconductor substrate 16 being used to provide a platform for operation of the subsequent process for producing an image sensor device. The material of the semiconductor substrate 16 is selected from monocrystalline silicon, polycrystalline silicon or amorphous silicon; the semiconductor substrate 16 may also be selected from compounds such as silicon, germanium, gallium arsenide, or silicon germanium; the semiconductor substrate 16 may also be other semiconductor materials. Illustratively, in the embodiment of the present invention, the semiconductor substrate 16 is a silicon substrate. In the embodiment of the present invention, a pixel device region is defined in the semiconductor substrate 16, the pixel device region includes a photodiode region 11 and a transfer transistor region 12, a first gate structure 14a and a sidewall material layer covering the surface of the first gate structure 14a and extending to cover the surface of the semiconductor substrate 16 corresponding to the photodiode region 12 are sequentially formed on the surface of the semiconductor substrate 16 corresponding to the transfer transistor region 12, where the sidewall material layer may be a multilayer structure, and specifically, the sidewall material layer in the embodiment of the present invention may be a multilayer structure composed of a high temperature oxide layer 18, an oxide layer 19, and a nitride layer 20, which are sequentially stacked in a direction away from the surface of the semiconductor substrate 16. Also, the photodiode region 11 may be a PD region having a certain junction depth obtained by an ion implantation process into the semiconductor substrate 16. The first gate structure 14a includes a gate oxide layer 17, and the gate oxide layer 17 further extends to cover the surface of the semiconductor substrate 16 corresponding to the photodiode region 12.
Further, as shown in fig. 4a, a device isolation structure 15 and a logic device region 13 separated from the pixel device regions (11 and 12) by the device isolation structure 15 are further formed in the semiconductor substrate 16, and a second gate structure 14b is formed on a surface of the semiconductor substrate 16 corresponding to the logic device region 13; the side wall material layer in step S1 further extends to cover the surfaces of the device isolation structure 15 and the second gate structure 14 b. Illustratively, the device isolation structure 15 may be a shallow trench isolation structure.
Furthermore, the side wall material layer may also be a single-layer structure made of nitride, such as silicon nitride, or a double-layer structure made of oxide and nitride, such as a stacked structure of silicon dioxide and silicon nitride, and the silicon nitride is located on the surface of the silicon dioxide.
In step S2, referring to fig. 4b, an oxygen treatment process is performed on a surface of the sidewall material layer facing away from the first gate structure 14a (and the second gate structure 14b), so that a surface of the sidewall material layer 110 facing away from the first gate structure 14a (and the second gate structure 14b) is converted into an oxynitride layer 20'.
In this embodiment, since the photoresist (photoresist) is "poisoned" due to the direct contact between the photoresist (photoresist) and the nitride layer 20 in the sidewall material layer in practical applications, and the subsequent process cannot clean the "poisoned" photoresist, thereby forming contaminants on the semiconductor substrate 16, in order to solve the problem, the method for manufacturing an image sensor according to the present invention needs to perform an oxidation process on the sidewall material layer before forming the patterned photoresist layer 21 (photoresist layer) in step S3, so as to convert the surface of the sidewall material layer from the nitride layer 20 to the oxynitride layer 20'. Specifically, the semiconductor substrate 16 may be placed in a reaction chamber containing a mixed gas of oxygen and nitrogen at a temperature of 200 ℃ to 300 ℃ for 20 seconds to 90 seconds, so that the nitride layer 20 included in the sidewall material layer is converted into plasma in the chamber to prepare for forming the patterned photoresist layer 21 by subsequent coating.
In step S3, referring to fig. 4c, a patterned photoresist layer 21 is formed, and the patterned photoresist layer 21 covers the photodiode region 11 and a portion of the surface of the oxynitride layer 20 'of the sidewall material layer corresponding to the transfer transistor region 12 to expose a portion of the surface of the oxynitride layer 20' of the sidewall material layer corresponding to the transfer transistor region 12.
In this embodiment, a photoresist layer (not shown) may be formed on the surface of the oxynitride layer 20' of the sidewall material layer, then, the semiconductor substrate 16 is exposed through a preset mask, and a pattern on the mask is copied onto the photoresist layer, so that the photoresist coated on the logic device region 12 and the pixel device region 13 is exposed by the mask, and the exposed photoresist is developed, so that the photoresist on the photodiode region 11 is retained, that is, a patterned photoresist layer 21 is formed, and the retained patterned photoresist layer 21 protects the photodiode region 11.
It should be noted that, in consideration of a slight offset in an actual photolithography process, the boundary position of the reserved area of the patterned photoresist layer 21 should be disposed on the first gate structure 14a of the pixel device area 12 to ensure that the photodiode area 11 is completely protected, and further, in consideration of that the formation position of the subsequent conductive plug 25 must be located in the photoresist developing area, the boundary position of the reserved area of the patterned photoresist layer 21 cannot exceed the edge of the first gate structure 14a of the pixel device area 12 by too much, and an optimal boundary position of the reserved area of the patterned photoresist layer 21 needs to be defined according to actual conditions. Specifically, the horizontal distance between the boundary of the patterned photoresist layer 21 formed in the step S3 along the side close to the logic device region 13 and the conductive plug 25 formed in the transfer transistor region 12 is 1/5-1/3L, where L is the width of the conductive plug 25 formed in the transfer transistor region 12 along the direction parallel to the surface of the semiconductor substrate 16. Preferably, as shown in fig. 4c and 4f, the distance from the conductive plug 25 of the pixel device region 12 to the edge of the first gate structure 14a of the pixel device region 12 close to the photodiode region 11 is L, and the distance from the boundary position of the remaining region of the patterned photoresist layer 21 to the edge of the first gate structure 14a of the pixel device region 12 close to the photodiode region 11 may be 1/3L-1/5L.
In step S4, referring to fig. 4d and referring to fig. 4c, the exposed spacer material layer is etched using the patterned photoresist layer 21 as a mask, so as to form a first spacer structure a on one side of the first gate structure 14 a.
In this embodiment, when the exposed sidewall material layer including the high temperature thermal oxide layer 18, the oxide layer 19 and the oxynitride layer 20' is etched in step S4, the patterned photoresist layer 21 is formed on the surfaces of the sidewall material layer in the photodiode region 11 and the partial transfer transistor region 12, so that the surface of the photodiode region 11 is not damaged by plasma in the sidewall etching process, thereby reducing dark current caused by surface damage, improving device performance, and ensuring normal operation of the pixel device region 12 and the logic device region 13. Further, for an image sensor with a large pixel size, i.e. an image sensor with a pixel unit size larger than 5 μm, the technical solution of the present embodiment can significantly reduce the dark current caused by the surface damage caused by the plasma due to the shallow ion implantation of the photodiode region 11 of the image sensor with a large pixel size.
In step S5, referring to fig. 4e and 4f, the patterned photoresist layer 21 is removed, and a subsequent process is performed on the semiconductor substrate 16 including the sidewall material layer covering the photodiode region 11 and a portion of the transfer transistor region 12, so as to form an electrical structure of the image sensor.
In this embodiment, the step of performing subsequent processes on the semiconductor substrate 16 in the step S5 includes: s5.1, sequentially depositing an oxide layer 22, a nitride layer 23, an interlayer dielectric layer 24 and a patterned hard mask layer (not shown) on the surface of the semiconductor substrate 16 including the side wall material layer covering the photodiode region 11 and part of the transfer transistor region 12; s5.2, with the hard mask layer as a mask, etching the interlayer dielectric layer 24 and the nitride layer 23 to form corresponding contact holes (not shown) in the transfer transistor region 12 and the logic device region 13, wherein the bottoms of the contact holes expose the tops of the first gate structures 14a or the second gate structures 14 b; and S5.3, forming a conductive plug 25 filled in the contact hole.
In this embodiment, the step of removing the patterned photoresist layer 21 on the semiconductor substrate 16, i.e. removing the photoresist layer 21 remained in the photodiode region 11, includes: the plasma gas of oxygen and nitrogen lasts for 30-90 seconds in the cavity at 200-300 ℃, so that the photoresist layer 21 is completely removed.
Further, after removing the photoresist layer 21, an oxide layer, such as silicon dioxide, may be formed on the semiconductor substrate 16, and then, the oxide layer covering the top surfaces of the first gate structure 14a and the second gate structure 14b is removed by photolithography and etching processes to form an oxide layer 22 shown in fig. 4e, so that the remaining oxide layer 22 covers all the surfaces of the semiconductor substrate 16 except the top surfaces of the first gate structure 14a and the second gate structure 14 b. Finally, a nitride layer 23 and an interlayer dielectric layer 24 are formed on the structure shown in fig. 4e, and a conductive plug 25 for electrically connecting the first gate structure 14a and the second gate structure 14b is formed in the interlayer dielectric layer 24 and the nitride layer 23, respectively, by an etching process.
In summary, in the manufacturing method of the image sensor provided by the present invention, the patterned photoresist layer is formed on the semiconductor substrate before the sidewall etching process (forming the first sidewall structure and the second sidewall structure) to cover the surface of the semiconductor substrate corresponding to the photodiode region, and then the subsequent etching process is performed to prevent the semiconductor substrate corresponding to the photodiode region from being completely exposed to the plasma environment in the etching process, so as to avoid damage to the surface of the semiconductor substrate corresponding to the photodiode region, thereby avoiding dark current caused by surface damage, ensuring normal functions of the pixel device region and the logic device region, and finally improving the performance of the image sensor.
The image sensor provided by the invention is manufactured by adopting the manufacturing method of the image sensor provided by the invention, the photoresist covers the photodiode area, so that the surface damage of plasma gas in an etching process to the photodiode area is avoided, the dark current caused by the surface damage is avoided, and the performance of the image sensor is improved.
It should be noted that, although the present invention has been described with reference to the preferred embodiments, the present invention is not limited to the embodiments. It will be apparent to those skilled in the art from this disclosure that many changes and modifications can be made, or equivalents modified, in the embodiments of the invention without departing from the scope of the invention. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention are still within the protection scope of the technical solution of the present invention, unless the content of the technical solution of the present invention is departed from.
It should be further understood that the terms "first," "second," "third," and the like in the description are used for distinguishing between various components, elements, steps, and the like, and are not intended to imply a logical or sequential relationship between various components, elements, steps, or the like, unless otherwise indicated or indicated.
It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention. It must be noted that, as used herein and in the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. For example, reference to "a step" or "an apparatus" means a reference to one or more steps or apparatuses and may include sub-steps as well as sub-apparatuses. All conjunctions used should be understood in the broadest sense. And, the word "or" should be understood to have the definition of a logical "or" rather than the definition of a logical "exclusive or" unless the context clearly dictates otherwise. Further, implementation of the methods and/or apparatus of embodiments of the present invention may include performing the selected task manually, automatically, or in combination.
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